Acoustical testing systems are known which provide calibrated sound pressure levels and frequencies. These are preferably designed to drive the device under test in an anechoic environment, i.e. free of sound reflections. Typically, this type of environment is impractical for small testing systems, especially at the low audio frequencies. The output of the device under test is then passed through a measuring system which is capable of providing readings of sound pressure level and/or harmonic distortion components. A significant drawback of these existing acoustical testing systems is that a highly-skilled operator is required for their proper operation due to their requirement for complicated interconnection of parts of the system combined with easily misinterpreted readout means. They generally use thermionic components with their attendant problems regarding long term stability, power comsumption and size.
An improvement over the above older systems was disclosed in U.S. Pat. No. 3,922,506 which disclosed a digital acoustical testing system that minimized operator error by providing automatic digital methods of presentation of data.
The present invention further minimized possibilities of operator error by providing computer control over the entire testing procedure rather than restricting the automatic processing to the measurement of the output of the device under test. The computer, operating under control of a hard-wired program, automatically steps the frequency of the acoustical drive signal, maintains its amplitude at a desired level, and, at the same time, monitors and digitizes the signal from the device under test, whereafter such digitized signals are digitally displayed and a hard copy made thereof in a digital or graphical format.
An object of the present invention is to provide an automatic acoustical testing system to minimize operator error and fatigue.
Another object of the present invention is the provision of an automatic acoustical testing system utilizing computer control for maximum flexibility of test procedures.
A further object of the present invention is to provide an automatic acoustical testing system having automatically adjusted and scaled circuit means which provides positive information to be processed thereby.
An additional object of the present invention is the provision of an automatic acoustical testing system that includes a digitally-controlled constant amplitude amplifier that makes use of digitized levels of an analog signal to provide a signal of substantially constant amplitude.
A still further object of the present invention is to provide a computer-controlled printer means for providing hard copy of electronically-processed information in a digital data format or graphical representation thereof.
These and other objects and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings. It is to be understood that variations of the present invention can be made without departing from the scope of the invention as defined herein.